McKinney-Byers: Investigation of Imja lake and potential remediation measures

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Glacial Flooding & Disaster Risk Management Knowledge Exchange and Field Training July 11-24, 2013 in Huaraz, Peru HighMountains.org/workshop/peru-2013

Investigation of the Imja Glacial Lake Outburst Flood Risk and Potential Remediation Measures, Khumbu, Nepal: Summary Report Daene C. McKinney University of Texas at Austin, Austin TX 78759 USA Alton C. Byers The Mountain Institute, Elkins, WV 26241 USA

During 2011 to 2013, the High Mountain Glacial Watershed Program (HMGWP) completed three field expeditions to Imja Lake in the Nepal Himalaya. The purpose of these expeditions and follow-­‐on analyses has been to quantify the risk of a Glacial Lake Outburst Flood (GLOF) from Imja Lake, the potential risk to downstream communities, and possible remedial measures to reduce that risk to an acceptable level. The studies that were performed include Ground Penetrating Radar (GPR) surveys of the terminal moraine and the Imja Glacier; a sonar bathymetric survey of the lake; and computer modeling of a potential GLOF from Imja Lake and downstream flooding. Detailed GPR surveys were conducted at Imja Lake to increase understanding of the internal structure of the terminal moraine of the former glacier tongue at Imja Lake, and the distribution of ice in the core of the moraine1. The GPR surveys were performed over most of the terminal moraine complex and around both sides of the outlet of the lake. The data obtained allowed for the mapping of the ice core of the moraine. The results of the GPR survey show that there is extensive ice present in the core of the terminal moraine complex at Imja Lake, with the thickest ice near the western end of the lake on the north side of the outlet. The ice in this region is several tens of meters thick and up to fifty meters thick in some places. Along the north and south sides of the outlet, the ice is between ten and twenty-­‐five meters thick. In some portions of the moraine on the south side of the outlet the ice thickness is up to forty meters. 1

Somos-Valenzuela, M. A., D. C. McKinney, A. C. Byers, K. Voss, J. Moss IV, and J. C. McKinney, Ground Penetrating Radar Survey for Risk Reduction at Imja Lake, Nepal, Submitted to Natural Hazards, December 2012


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